Parallel Redstone.

I propose adding "insulated" redstone. It could look like redstone dust placed on a half-slab, or perhaps resemble a repeater or comparator sitting on its own slab.

The difference from standard redstone is that it does not activate any adjacent mechanisms.
It isn't washed away by water, and it can be placed in specific directions—much like rails.

You can power it and read its signal using repeaters and comparators.

In my opinion, this would make mechanisms slightly more compact. Unlike standard redstone, it wouldn't even activate the block it sits on, which would be useful for certain types of contraptions.